It is important in microlithography to illuminate an object field with a predetermined intensity distribution. Unwanted intensity variations should be avoided here. However, when using multi mirror arrays (MMAs), there can be unwanted intensity variations in the object plane due to the gaps, due to the construction, which are present between the mirrors.
Multi mirror arrays for illumination optical units of a projection exposure apparatus are known, for example, from WO 2010/099807 A1 and DE 10 2012 207 866.5.